Removal of liquid refrigerant from the supply line to a compressor



J. W. OBREITER, JR REMOVAL OF LIQUID REFRIGERANTS FROM THE SUPPLY LINE T0 COMPRESSORS Filed Sept. 17, 1947 Feb. 8, 1949.

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I fvaporafor F V 2 Q m M W 0 MW. m 0 w J W W Patented Feb. 8, 1949' I I 6 UNITED STATES PATENT orrlca' REMOVAL OF LIQUID REFRIGERANT FROM THE SUPPLY LINE TO A COMPRESSOR Joseph W. Obreiter, Jr., Glen Ridge, N. J. Application September 17, 1947, Serial No. 774,643

, 10 Claims. 62-415) 1 2 This invention relates to refrigeration and more passes into an evaporator 24; and the outlet of .especially to the removal of liquid refrigerant the evaporator is connected by piping 25, with a from the supply line ofacompressor. The invenseparator 26. The outlet of the separator is tion is concerned with refrigeration systems that connected with the intake of the compressor ill have a closed circuit in which the refrigerant 5 by a conduit 26.

passes successively through a compressor, con- A thermostatic controlling mechanism is condenser, and evaporator; and then back to the nected with the expansion valve i8, and this intake i e of th compressor, mechanism consists of a bulb 30 located adjacent Any liquid refrigerant that is not vaporized in the low pressure or hot side of the evaporator the evaporator, and that travels-back to the com- 24, and a capillary tube 3| through which the pressor, endangers the compressor lubrication valve i8 is actuated with the development of a by mixing with the compressor crankcase oil, or temperature in excess of that require in the even'washing out compressor crankcase 011 via operation of the apparatus when the load upon the compressor discharge. Liquid refrigerant the evaporator is well below its peak. The bulb reaching the compressor inlet is also dangerous an is preferably strapped to the piping 25. This because of the possibility of damage to the comcontrol feature is old and well known in the pressor from slugs of the liquid refrigerant and refrigerating art, oil. The separator 25 is a gravity separator and the It is an object of this invention to provide an piping 25 opens into the separator 26. at a region improved method and apparatus for removing somewhat below the top of the separator. A taliquid refrigerant from the conduit between an pering outlet 34, at the top of the separator 26, evaporator and the intake side of a compressor. is connected with the conduit 28 by a fitting 35.

One feature of the invention relates to appa- When the refrigeration system is in operation, ratus in which liquid refrigerant is removed vaporized refrigerant from thepiping follows from a compressor supply line, in whichthere 1s 25 the course indicated by thedotted arrow 31 entrained oil, without having the separation apand passes directly to the outlet 34, and through paratus become oil logged. Another feature rethe conduit 28 to the intake side of the comlates to the vaporizing of any liquid refrigerant pressor I0. v that passes beyond the evaporator, and to simple Liquid refrigerant and oil flow by gravity, as apparatus in which the liquid refrigerant is vaindicated by the dotted arrow w rd a otporized and the vapor returned to the system tom wall 4| at the lower end of the separator 26. without interfering in any way with the efficient In the construction illustrated, the bottom wall operation of the refrigeration cycle. The pre- 4| of the separator 26 co p s s the top the ferred form of the invention may increase the heat exchanger i2, but it will be understood efliciency of the refrigeration system with which that the separator 26 and heat exchanger l2 can t is 11591 be separate units connected by the necessary Other objects, features and advantages of the conduits. I

inventionwill appear or be pointed out as the de- Liquid that gathers in the bottom of the sepascription'proceeds. rator 26 drains downward through a tubing 43 The drawing is a diagrammatic illustration of 40 and through a'check valve '44 near the upper end the preferred form of the invention. of the tubing. The liquid refrigerant from the The refrigeration system shown in the drawtubing 43 enters a coil 46, and while the reing includes a compressor ID that delivers comfrigerant is in the tubing 43 and coil 46, it is in pressed refrigerant, in vapor phase, through an heat-exchanging relation with the hot comoutlet pipe ii to a heat exchanger I 2. The repressed gases that now through the heat exfrigerant vapor passes through the heat exchanger l2 and into contact with the outside'surchanger i2, and piping l3, to a condenser i4. faces of the tubing 43 and coil 46.

In the condenser l4 the refrigerant is condensed The liquid refrigerant that is vaporized in the to a liquid and discharged through condenser coil 46, and in the tubing 43 below the check outlet piping I! to an expansion valve l8.. The valve 44, cannot flow back through the tubing 43 condenser I4 is shown with connections 20 and because'of the check valve. The vaporized re- 2| for the supply and discharge of cooling liquid, frigerant escapes from heat exchanger through such as water, that is used to extract heat from an outlet pipe. '46 thatdischarges into the outlet the condenser. s 34 of the separator 26. -As soonas the liquid Beyond the expansion valve 16, the refrigerant in the coil 46 has been vaporized, back pressure against the check valve 44 is relieved, and more liquid from the separator 2 can flow downward through the tubing 43 and check valve 44.

The refrigeration system includes a closed circuit, and the liquid that is separated from the gas stream in the separator 26 can be considered as withdrawn from the circuit and later returned to the circuit when it is vaporized and again enters the stream of evaporated refrigerant flowing from the evaporator 24. By thus withdrawing the liquid, heat can be applied to it without increasing the temperature of the evaporated refrigerant passing from the evaporator to the compressor. Another advantage is that the pressure in the heat exchanger in which the separated liquid refrigerant is vaporized need not be the same as in the low pressure side of the refrigerant circuit. For example, when the liquid in the coil 48 is being vaporized, the pressure in the coil will at times be;higher than the pressure in the piping 25, and must be higher in order to hold the check sources of heat to evaporate the liquid refrigerant that is collected by the separator 26.

valve 44 closed. This higher pressure causes increased velocity at the discharge end of the pipe 48 and the flow of vapor from the end of the pipe 48 into the tapered outlet 34 gives an aspirator action that aids the flow of evaporated refrigerant from the pipe into the separator outlet 34.

It is a feature of the invention that the liquid evaporated in the coil 44 discharges into the separator 28 above the level of the liquid in the separator.- This permits the vaporized refrigerant to be discharged from the coil 46 at a sufficiently high velocity to entrain oil and carry it, extrained in the vapor, back through the conduit 28 to the compressor. If there were no check valve 44 and the vaporized refrigerant from the coil 46. escaped upward through the tubing 43,

and through the accumulated liquid in the bottom of the separator 26, the velocity of the vaporized refrigerant would be considerably lower and the sump of the separator might become oil logged.

It is also a feature of the invention that the discharge end of the pipe 48 is not only located above the liquid level in the separator but is also located above the level at which the piping 25 opens into the separator 26. This means that the vaporized refrigerant from the pipe 48 enters into the stream of vapor passing to or through the outlet 34- and does not encounter the downwardly moving particles of liquid refrigerant and oil from the piping ,25.

It will be understood communicate with the conduit 28 beyond the separator 26 and still embody this feature of having-the vaporized refrigerant from the heat exchanger l2 join the vaporized refrigerant from evaporator 24 at a region beyond that at which liquid and vapor from the evaporator were separated.

The heat exchanger l2"is merely representative of apparatus for heating the liquid refriger-- ant from the separator 26. By making use of the refrigerant, on the high pressure side of the evaporator, as the source of heat for the heat exchanger l2, the refrigerant reaches the evaporator 24 at a lower temperature and produces more cooling in the evaporator. The efliciency of the system is thus increased.

It is not necessary, however, to use the refrigerant on the high pressure side of the compressor as the source of heat for evaporating the liquid from the separator ,26, and in cases where the separator is not located close to the compressor or condenser, it may be advantageous to use other Various changes and modifications can be made in the form of the invention described, and some features of the invention can be used alone or in different combinations without departing from the invention as defined in the claims.

I claim as my invention:

1. In the operation of a refrigeration system in which compressed refrigerant is condensed, evaporated to produce refrigeration, and returned to a compressor, the improvement that comprises withdrawing any remaining liquid refrigerant from the evaporator refrigerant at a region along the course of circulation of the evaporated refrigerant through the system, transferring the liquid to another region of higher temperature, vaporizing said withdrawn liquid by the application of heat at the region of higher temperature, and returning the resulting vaporized refrigerant to the course of circulation of the evaporated refrigerant along a course that lay-passes the region at which the liquid was withdrawn and at a region downstream from that at which said liquid was withdrawn at a region beyond that at which the liquid was withdrawn from the evaporated refrigerant and ahead of the intake of the compressor.

2. In the operation of a closed-circuit refrigeration system in which compressed refrigerant is condensed, evaporated, recompressed and repeatedly circulated through the system, the improvement'that comprises withdrawing from the that the piping 48 can 4 evaporated refrigerant any oil and other entraineid liquid, drainin such liquid from the refrigeration circuit, .returning the oil to the refrigeration circuit by entraining the oil in refrigerant that is evaporated from the liquid state at the region to which the oil is drained, the entrained oil being returned to the circuit by a course different from the course through which the oil was drained, and returning the entrained oil to the circuit at a region down stream from that at which liquid was withdrawn from the evaporated refrigerant.

3. In the operation of a closed-circuit refrigeration system'in which compressed refrigerant is condensed, evaporated and reoompressed in repeated cycles, the improvement that comprises withdrawing oil and liquid refrigerant from the circuit at a region between the evaporator and the inlet of the compressor, heating said oil and liquid refrigerant until the liquid refrigerant is vaporized, and returning the vaporized refrigerantinto the stream of evaporated refrigerant in the circuit, down stream from the region at which the oil and liquid were withdrawn, and with the oil entrained in and carried by the vaporized refrigerant.

4. In a refrigerating apparatus having a compressor. condenser, an evaporator and connections therebetween, means for preventing liquid refrigerant from reaching the compressor comprising a gravity separator in the connection between the evaporator and the compressor, a heat exchanger arranged to receive liquid refrigerant from the separator and hot gases-from the compressor, and a connection for vaporized refrigerant from the heat exchanger to the intake side of the compressor.

5. In a refrigerating apparatus having a compressor, condenser, an evaporator and connections therebetween, means for preventing liquid rethe evaporator and the compressor, a heat exchanger, a connection between the bottom of the separator and one side of the heat exchanger, a source of heat at the other side of the heat exchanger, and a connection from the first mentioned side of the heat exchanger to the intake side of the compressor.

6. In a refrigerating apparatus having a compressor, condenser, an evaporator and connections therebetween, means for preventing liquid refrigerant from reaching the compressor comprising a gravity separator in the connection between the exaporator and the compressor, a heat exchanger, a connection between the bottom of the separator and one side of the heat exchanger, a check valve in said connection, a source of heat at the other side of the heat exchanger, and a connection from the first mentioned side of the heat exchanger to the intake side of the compressor.

7. In a refrigerating apparatus having a compressor, condenser, an evaporator and connections therebetween, means for preventing liquid refrigerant from reaching the compressor comprising a closedgravity separator in the connection between the evaporator and compressor, an inlet from the low pressure side of the evaporator entering the separator near its top, an outlet from the separator at the bottom for liquid refrigerant, an outlet from the separator near its top for gaseous refrigerant, a heat exchanger arranged to receive liquid refrigerant from the bottom outlet of the separator and to return gaseous refrigerant to the separator adjacent its top outlet.

8. In a refrigerating apparatus having a compressor, condenser, an evaporator and connections therebetween, means for preventing liquid refrigerant from reaching the compressor comprisfor gaseous refrigerant, a coil located externally of the separator having one end connected with .erant, an outlet from the separator near its top for gaseous refrigerant, a coil located externally of the separator having one end connected with the bottom outlet of the separator and the other opening into the separator adjacent its upper outlet, a casing surrounding the coil, and connections from the compressor to the casing and from the casing to the condenser.

10. In a refrigerating apparatus including a compressor, a condenser, an evaporator, and connections joining the different elements of the apparatus in a closed system for circulation of refrigerant, a separator in the connection between the evaporator and the low pressure side of the compressor for preventing liquid refrigerant from passing to the compressor,aheat exchangerin position to receiveliquid refrigerant from the separator, and connections for circulating refrigerant on the high pressure side of the evaporator through the heat exchanger to supply heat for evaporating the refrigerant from the separator.

JOSEPH W."OBREI'I'ER,, JR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name- Date 1,106,287 Doelling Aug. 4, 1914 2,440,146 Kramer Apr. 20, 1948 

